Figure 2 Directional selection under low watering (red) and high watering (blue) in the greenhouse. The analysis is based on the genotype trait-means and the relative fitness of genotypes, both computed across low water levels (15ml, 20ml) and high water levels (50ml, 90ml), excluding the intermediate water level (30 ml) and followed by standardization (zero mean, 1 SD) per population (SA and M) and watering level (high and low). Differential selection between water levels is indicated by their interaction with the tested trait (* p< 0.05, ** p< 0.01, *** p< 0.001).